Headlights or the like vehicle lighting units can be disposed at right and left front end areas of a vehicle body, and they may be provided with aiming mechanisms configured to adjust their optical axes. Such an aiming mechanism can be configured such that a pivot attached to a reflector that holds a light source is supported by a pivot holder provided to a housing while the pivot is freely rotatable. The aiming mechanism can further be provided with an adjustment bolt that is configured to be rotatable. The rotation of the adjustment bolt can achieve the optical axis adjustment by inclining the reflector.
In the vehicle lighting unit, the above described aiming mechanism can often include a pivot holder integrally formed with the housing in order to reduce the number of required parts (see, for example, Japanese Patent Application Laid-Open No. Hei. 09-007405 (1997)). One example of the pivot holder integrally formed with the housing is illustrated in FIGS. 1 and 2.
FIG. 1 is a perspective view illustrating part of a conventional pivot holder, and FIG. 2 is a side sectional view illustrating how to mold the conventional pivot holder. This conventional pivot holder 111 can be a cylindrical boss shape and integrally molded with the housing 102 at its rear surface to be projected therefrom. A spherical seat 111a can be formed inside the pivot holder 111 so as to be opened forward, and an engagement portion 111b can be formed at the rim of the opening of the spherical seat 111a. Furthermore, three slits 111c can be formed in the pivot holder 111 at its circumferential surface in the front-to-rear direction so as to allow the engagement portion 111b to be elastically deformed.
With the above configuration, a not-shown ball formed at the tip of a pivot can be fit to the pivot holder 111. Specifically, when the ball is allowed to pass through the engagement portion 111b of the pivot holder 111, the engagement portion 111b is pushed backward. After passing through the engagement portion 111b, the ball is fit within the spherical seat 111a while the engagement portion 111b can be elastically returned to its original position, so that the ball can be reliably retained to be prevented from falling off. By fitting the ball of the pivot to the pivot holder 111, the pivot and the not-shown reflector supporting the pivot can be freely rotated in all directions with the pivot holder 111.
When molding the pivot holder 111 integrally with the housing 102 as illustrated in FIG. 1, a metal mold 120 must be withdrawn from the metal mold 120 in the direction of an arrow in the drawing after the completion of molding as illustrated in FIG. 2. When the mold 120 is forcedly withdrawn, the engagement portion 111b is elastically deformed with the provision of three slits 111c formed in the pivot holder 111. However, if an excessive force during withdrawn is applied to the engagement portion 111b, the engagement portion 111b may be plastically deformed, and the engagement portion 111b cannot be returned to its original shape after the mold is withdrawn and may be enlarged in diameter. In this case, the support of the pivot may stagger, resulting in failure of illumination by the vibration of the reflector when the vehicle lighting unit is lit at night.